An estimated 20-30% of the four million Americans with hepatitis C infection (HCV) are projected to develop advanced fibrosis and cirrhosis after 2-3 decades of infection. Differences in exposure to fibrosis-promoting risk factors like alcohol abuse likely explain some of this difference in fibrosis risk. However, current research suggests that genetic factors may also influence the risk of advanced fibrosis in HCV patients. Two factors that research has repeatedly shown to be associated with development of advanced liver disease are male gender and abdominal obesity. However, the specific role genetic factors, including those related to male sex hormone receptor or androgen receptors (AR) and to insulin resistance (IR) associated with abdominal obesity, may play in fibrosis risk remains unclear. The goal of the proposed study is to ascertain the role that changes in AR and IR genes play in increasing risk of advanced fibrosis. The associated specific aims are: 1) to identify and collect data on a large and representative cohort of male veterans with HCV infection; 2) to test the hypothesis that 'high risk variants of genes related to IR either alone or in conjunction with abdominal obesity increase fibrosis risk; and 3) to test the hypothesis that 'high risk' variants of genes related to AR also increase fibrosis risk. Aim 1 will be accomplished with standard epidemiology methods for cohort identification and will be performed at the Michael E. DeBakey VA. Aims 2 and 3 will be addressed through a case-control study in which cohort members with advanced fibrosis (cases) are compared to those with mild fibrosis (controls). The research plan, didactic training and outstanding mentoring environment will work together to allow the principal investigator to acquire new skills as well as refine existing skills in the development and execution of novel genetic epidemiology studies, allowing her to develop into an independent investigator in genetic epidemiology of chronic liver and digestive disorders.